Method for the production of a printing plate using the dual-feed technology

Abstract

A method for producing printing plate precursors by dual-feed technology is described. The obtained printing plate precursors contain polymer particles in the photosensitive layer and show high print run stability.

We claim:  
     
       1. Method for producing a printing plate precursor comprising: 
       (a) providing a first solution comprising a thermoplastic polymer and a solvent or solvent mixture A, solvent A being capable of dissolving the thermoplastic polymer, the thermoplastic polymer being soluble in organic media but insoluble in alkaline media, and a conventional photosensitive composition;  
       (b) separately providing a second solution comprising a solvent B which is capable of dissolving a photosensitive composition but not the thermoplastic polymer and which is less volatile than solvent A;  
       (c) separately feeding the solutions of steps (a) and (b) above to an in-line mixer unit; and  
       (d) applying mixture from the mixer unit to a printing plate substrate thereby forming a coating on the substrate,  
       wherein a conventional positive or negative working, or electrophotographically working photosensitive composition C is present in at least one selected from the first solution and the second solution. 
     
     
       2. The method according to  claim 1  wherein the photosensitive composition C is present in the first solution. 
     
     
       3. The method according to  claim 1  wherein the photosensitive composition C is present in the second solution. 
     
     
       4. The method according to  claim 1  wherein the total amount of the photosensitive composition C is present in both the first and second solution. 
     
     
       5. The method according to  claim 4  wherein about 5 to about 99 wt% of the photosensitive composition C is present in the first solution and the remaining portion is present in the second solution. 
     
     
       6. The method according to  claim 1  wherein the thermoplastic polymer is at least one selected from the group consisting of polystyrene, styrene acrylonitrile copolymer, polycarbonate, polymethylmethacrylate, polyvinylchloride, polymethylpentene, acrylonitrile-butadiene-styrene terpolymer and polysulfone. 
     
     
       7. The method according to  claim 1  wherein at least one of the group consisting of the first solution and second solution further contains a surfactant. 
     
     
       8. The method according to  claim 1  comprising applying mixture using a slot coater. 
     
     
       9. The method according to  claim 1  wherein the weight ratio of solvent A to solvent B is about 99:1 to about 10:90. 
     
     
       10. The method according to  claim 9  further comprising producing a printing plate precursor at a line speed of about 5 to about 100 m/min. 
     
     
       11. The method according to  claim 1  wherein the substrate is selected from the group consisting of mechanically and/or electrochemically grained aluminum, grained aluminum subjected to an anodizing treatment, plastic foils which may optionally be laminated to an aluminum foil, and a grained and optionally anodized aluminum substrate which is further subjected to a hydrophilizing treatment. 
     
     
       12. Printing plate precursor obtainable by the method of  claim 11 . 
     
     
       13. The method according to  claim 1  further comprising transferring the coated printing plate substrate to a drying unit. 
     
     
       14. The method according to any one of  claim 1  or  claim 13  further comprising subjecting the coated printing plate substrate to a baking treatment. 
     
     
       15. Printing plate precursor obtainable by the method of  claim 1 . 
     
     
       16. The printing plate precursor according to  claim 15  wherein the coating has a dry weight of about 0.25 to about 10 g/m 2 . 
     
     
       17. The printing plate precursor according to  claim 15  wherein the coating comprises particles of the thermoplastic polymer having a size of about 0.1 to about 10 μm.